Good question. I thought http://hpmor.com/info/ would cover the licensing, but nope. Some googling doesn't turn up any explicit licensing either.
That page leaves it clear:
"All fanfiction involves borrowing the original author’s characters, situations, and world. It is ridiculous to turn around and complain if your own ideas get borrowed in turn. Anyone is welcome to steal anything from any fanfiction I write."
You know the drill - If it's worth saying, but not worth its own post (even in Discussion), then it goes here.